The long term goal of this research is to elucidate the mechanisms by which vitamin E functions in the regulation of differentiation, maintenance, and function of the mammalian testis. High levels of polyenoic fatty acids are present in testis; the turnover of arachidonic acid is related to testicular development and appears to be regulated by vitamin E. Arachidonic acid is the precursor of the principal prostaglandin synthesized by rat testis, i.e. prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha). Biosynthesis of PGF2 alpha parallels the differentiation of the testis, and the profile of the synthetic activity is affected by vitamin E. The enzyme that converts PGE2 to PGF2 alpha (prostaglandin E-9 ketoreductase, E9KR) has an unusually high specific activity in testis, and the activity of this enzyme also reflects the maturation of the testis and appears to be influenced by vitamin E. The objectives of the current proposal are to determine the role(s) of prostaglandin on testicular development and function, and the effect of vitamin E on these processes. The following studies will be performed. Prostaglandin synthesis will be determined in isolated germ cells at specific stages of spermatogenesis, Sertoli cells, and Leydig cells. Activities of the enzymes that inactivate prostaglandins (prostaglandin 13, 14 reductase and 15-hydroxydehydrogenase) will be studied. Using purified enzyme, the properties and regulation of E9KR will be investigated. Isolated testicular cells will be used to test prostaglandin-cyclic nucleotide-interactions that we have recently observed. Comparative studies will be done using testes of vitamin E-deficient and control rats during testicular development. Reversibility of the effect of vitamin E on prostaglandins will be tested in the hamster, a model in which vitamin E therapy restores normal testis morphology and function. Since prostaglandins have regulatory effects on cells in mitosis and on differentiation, the relationship between arachidonic acid, vitamin E, and prostaglandins in testis needs to be evaluated.